Haha, in fact it's a newly-coined word for describing those people who put all their strength in taking GRE and TOFEL exams in order to go abroad. Please don't try to interpret this word literally, because that won't make any sense. :DD Sometimes we take the first syllable of a word as its short form, and for those foreign words we find some words with similar sound to substitute for them. Taking GRE exams, in Chinese we say "考寄"; taking TOFEL exams, in Chinese we say "考托". "一族" is a quite popular way to address a group of people with some common features. So you can guess what "寄托一族" means. And I don't think it's a slang, it's more like a kind of cyberword. If you use this word to talk with a middle-aged Chinese man he may not understand you. XDD